As medical science has become more sophisticated, increasing use of intravascular procedures has taken place. In vascular disease, the use of arterial endarterectomy as well as percutaneous balloon dilation of vessels for pathologic stenosis have become a routine hospital procedure. Although often successful, a common complication is occurrence of vessel wall abnormalities after the procedure. The abnormalities include recurrent stenosis due to atherosclerosis, smooth muscle proliferation, loss of vessel wall integrity as a result of fibrosis and thrombosis of the vessel. Endothelial injury or removal is one of several common denominators inherent to vascular procedures and current data suggests that spontaneous re-endothelialization of these injuries may occur slowly, partially or not at all. The major hypothesis of our research is that re-endothelialization of the vessel wall following injury will prevent the occurrence of post-injury stenosis. The major objective of this proposal is to examine the interaction of previously isolated endothelial cells (EC) with components of the de-endothelialized native vessel wall. We will examine the temporal events involved during the deliberate restoration of an intact endothelial lining upon a vessel wall immediately following injury. Experiments have been designed to answer the following questions: 1. What mechanisms are involved in the re-endothelialization of injured vessel walls using human microvessel and large vessel EC? 2. What are the effects of depth and type of vessel wall injury on re-endothelialization? 3. What are the effects of substrate proteins and method of seeding on re-endothelialization? The interaction between EC and components of the vessel wall will be examined by measuring: 1. The process by which previously isolated EC approach and attach to the surface. 2. The temporal dynamics of cell spreading and monolayer formation. 3. The morphology of the subsequent monolayer.